Studies on Metal Complexes Derived from Physiologically Active Quinoxaline Derivatives

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Addis Ababa Universty


Coordination compounds, with bonds between a central metal atom and surrounding ligands, play critical roles in biology, biochemistry and medicine, controlling the structure and function of many enzymes and their metabolism. They play similarly vital roles in many industrial processes and in the development of new materials with specifically designed properties. Thus synthesis and study of such complexes is very important. In this lab work, equimolar quantities of o-phenyldiamine and oxalic acid dihydrate were condensed in 5N HCl under reflux to 2,3-quinoxalinedione. Refluxing of 2,3-quinoxalinedione with phosphorus (V) chloride as well as with thionylchloride gave 2,3 dichloroquinoxaline which was then treated first with hydroxylamine hydrochloride to afford a new ligand 2,3- quinoxalinedioxime (QXDO) and secondly with N-(aminoformimidoyl)phenol to give quinoxaline-2,3-bis-[N-(aminoformimidoyl)phenol] (QXAP) both of which contain nitrogen and oxygen donor atoms. However, the formation of QXAP was unsuccessful as it was confirmed by 1H NMR. Thus QXDO was further complexed with divalent metal salts to give different complexes. New metal complexes of nickel and copper with quinoxalinedioxime (QXDO) were prepared. The complexes were characterized by elemental analysis, conductance measurements, atomic absorption, IR, NMR and UV spectroscopy and magnetic moments. QXDO behaves as a bidetate ligand. Key terms: Quinoxaline, o-phenyldiamine, salicylaldehyde, hydrazine, 2,3-quinoxalinedione (QXD), 2,3-dichloroquinoxaline (DCQX), 2,3-quinoxalinedioxime (QXDO).



Quinoxaline; o-phenyldiamine; salicylaldehyde; hydrazine; 2;3-quinoxalinedione (QXD); 2;3-dichloroquinoxaline (DCQX); 2;3-quinoxalinedioxime (QXDO).